1

AIPMT 2012 Prelims

Which one of the following statements is incorrect about enzyme catalysis?
A
Enzymes are mostly proteinous in nature.
B
Enzyme action is specific.
C
Enzymes are denatured by ultraviolet rays and at high temperature.
D
enzymes are least reactive at optimum temperature.

Explanation

Enzymes are most reactive at optimum temperature. The optimum temperature for enzyme activity lies between 40°C to 60°C.
2

AIPMT 2012 Prelims

In Freundlich adsorption isotherm, the value of 1/n is
A
between 0 and 1 in all cases
B
between 2 and 4 in all cases
C
1 in case of physical absorption
D
1 in case of chemisorption.

Explanation

${x \over m} = k.{p^{{1 \over n}}}$

Where ${x \over m}$ is the ratio of amount of adsorbent to the amount of adsorbate.

The value of n is always greater than 1. So, the value of ${{1 \over n}}$ lies between 0 and 1 in all cases.
3

AIPMT 2011 Prelims

If x is amount of adsorbate and m is amount of adsorbent, which of the following relations is not related to adsorption process?
A
x/m = $f$(p) at constant T
B
x/m = f(T) at constant p
C
p = f(T) at constant (x/m)
D
${x \over m} = p \times T$

Explanation

${x \over m} = p \times T$ is incorrect.

4

AIPMT 2007

The Langmuir adsorption isotherm is deduced using the assumption
A
the adsorption sites are equivalent in their ability to adsorb the particles
B
the heat of adsorption varies with coverage
C
the adsorbed molecules interact with each other
D
the adsorption takes place in multilayers.

Explanation

Langmuir adsorption isotherm is based on the assumption that every adsorption site is equivalent and that the ability of a particle to bind there is independent of whether nearby sites are occupied or not occupied.